Consumer products known as “wipes” can be used for a variety of purposes, including, but not limited to the following: cleaning of the skin (e.g. baby wipes); cleaning of surfaces (e.g. disinfecting wipes and glass-cleaning wipes); application of skin ingredients (e.g. wipes for applying sunscreen). Wipes are generally two-dimensional sheets that are formed from a variety of substrates and that are saturated with a liquid composition formulated to achieve their intended use. When originally conceived, wipes may have been intended to generally mimic paper towels, though wipes tend to be of smaller dimensions. The substrates, or basesheets, used to form wipes products can include fibrous materials, film materials, foam materials or combinations of such materials. The fibrous materials can be selected from cellulose (also known as “pulp”) fibers and petroleum-derived polymeric fibers. The basesheet can have a uniform composition of fibers (whether a single type of fiber or a mixture of different types of fibers) or the basesheet can be composed of two or more layers of fibers. Within an individual layer, the fibers can be all of the same type or there can be a mixture of different types of fiber within the individual layer. Between individual layers, there can be similar diversity of fibers and fiber compositions.
Wipes products are typically saturated with an aqueous liquid composition. With proper storage, the wipes will remain wet for long periods of time. However, over time and depending on the integrity of the package holding the wipes, the wetness will change to a “moist” feeling and, eventually, the wipes will dry out. For some uses, the wetness of the wipes is desired to enhance performance of the primary function of the wipes. For example, “baby” wipes that are used during diaper changes for infants and toddlers are wet to aid with removal of bodily waste that may be present on the child's skin as a result of wearing a diaper or other absorbent article. The aqueous composition of the baby wipe is not intended, per se, to transfer to the skin of the child. However, the aqueous composition must be very gentle and non-irritating to skin that can be prone to irritation and rash. In fact, the aqueous compositions used with baby wipes are frequently more than 95% water and may even have 99% water. Another example of the aqueous composition enhancing the primary function of the wipe is with cleaning wipes. The aqueous composition used with cleaning wipes will be formulated to perform the desired cleaning function. Exemplary functions of cleaning wipes include disinfecting, removal of stains and cleaning of special surfaces such as stainless steel and electronics. As with the baby wipes, the aqueous composition of the cleaning wipe is not intended, per se, to transfer to the surface being cleaned.
In other wipes products, it may be desirable to have the aqueous composition actually transfer and be deposited on the surface to which the wipe is coming into contact. For example, wipe/towelette products are sold for the purpose of applying sunscreen and insect repellant. Vitamins, such as Vitamin E, may also be applied to the skin by transfer of a composition from a wipe to the skin. Depending on the formulation of the aqueous composition, users of such wipes products may experience different degrees of success in feeling like the desired composition was sufficiently transferred to the skin. The consequences of unsuccessful transfer of the composition to the skin can cause injury, as in the case of a wipe intended for aiding application of sunscreen. Unfortunately, users of existing wipes products are not consistently confident about the amount of composition transferred to the desired surface; one or more the following could contribute to the lack of confidence: (1) not knowing whether the composition actually transferred to the surface; (2) the wipe feeling dry or insufficiently saturated with the composition to effectuate a transfer; and (3) the desired outcome does not occur (e.g. user experiences a sunburn).
There remains a need for a composite structure, such as a wipe, that is capable of reliably delivering a composition initially present in the wipe to a target surface. There further remains a need for a composite structure that has a sensory cue to assure a user that the composition was, indeed, transferred to the target surface. There is a need for a composite structure that maintains structural integrity while acting as a reservoir for a liquid intended to be transferred to a target surface. Additionally, there remains a need for a composite structure that has a structure of a support layer and a reservoir layer where the reservoir layer holds an aqueous-type composition that is a liquid at temperatures below the intended target surface temperature (e.g. human body temperature) but that changes into a hydrogel when exposed to the temperature of the intended target surface.